Not sure if anyone is aware or if it is relevant for anyone else but you can get free nappies/pull ups from your HV.
My DD has global delayed development and is still in nappies. Like to wear pull ups in the day but wears them like nappies.
As she is now 3 and I get diability living allowance for her, my HV arranged for me to get free nappies for her. Got my first delivery last week (6 packets) which is going to make a bit of a difference to my shopping bill.
If anyone else's child is still in nappies at an older age, let them know they get free nappies.